'fastcopy_I' is part of the implementation of memcpy, realloc, etc in msvcrXX.dll on Windows. It doesn't really add any value to stack traces since it isn't a public API, so it should probably be skipped from the frame list entirely. The callers of fastcopy_I should be preserved in the frame list, however, as errors could be the result of a heap corruption that the calling frame has nothing to do with. An example crash report with fastcopy_I at the top of the stack is https://crash-stats.mozilla.com/report/index/5c3c3f81-23fb-4a6e-a032-ba6b22110919.
All of the memcpy type functions are right now in the prefix list rather than the irrelevant list - just want to confirm which of those you want, since it sounds like you want to add this one to the irrelevant list. See definitions here: https://wiki.mozilla.org/Breakpad/Skip_List_How_To
fastcopy_I is a private function in Microsoft's implementation of memory allocation functions. It will always be called by a public API, like memcpy, realloc, memmove, etc. I would think it would be safe to hide. But, being able to search on this symbol might be a good way to aggregate all the memory-related/heap-corruption bugs on Windows. So maybe it is best to move to the prefix list. I'll defer to people with more experience.
Waiting on info to implement.
Kairo asked me to do this today, so without more input from anyone, I'm adding it to the prefix list.
Commit pushed to master at https://github.com/mozilla/socorro https://github.com/mozilla/socorro/commit/6d551c0a63f04f58e7212a451d0fab2495426e60 Fixes bug 687672, add fastcopy_I to the prefix skiplist